The present invention relates to an electric compressor for a vehicle.
Japanese Patent Application Publication No. 2008-301688 discloses an electric compressor for a vehicle. In the electric compressor of the above Publication, a stator of an electric motor is of annular shape and includes a stator core having slots formed by a plurality of teeth and coils wound in the slots. The stator core is formed by a plurality of laminated core plates made of a metallic magnetic material. The coils are formed by wave winding. A U-phase coil, a V-phase coil, and a W-phase coil are provided in first, second, and third groups of slots, respectively.
An interphase insulating sheet is provided between the coil end of the U-phase coil that is disposed outside the first group of slots and the coil end of the V-phase coil that is disposed outside the second group of slots. Similarly, the interphase insulating sheet is provided between the coil end of the V-phase coil that is disposed outside the second group of slots and the coil end of the W-phase coil that is disposed outside the third group of slots. The coil end of each phase coil and the interphase insulating sheet are laced by a string.
In the electric compressor of the above Publication, the coil end of each phase coil and the interphase insulating sheet are laced by a string passed in a space (hereafter referred to teeth space) formed between the coil end and the tooth. A crochet needle is used for lacing by a string. The crochet needle is reciprocable in the teeth space in the radial direction of the stator core.
In a stator core that is formed by laminating a plurality of core plates, the stator core plates are fixed together by crimping so as to prevent the core plates from being delaminated. Each core plate has a projection and a recess on the opposite sides thereof at the crimped portion. Specifically, the projection and the recess of any two adjacent core plates are engaged with each other thereby to fix the core plates together. The crimped portions formed by the projections and the recesses of the core plates may be formed at a plurality of positions that are spaced at equiangular intervals and adjacent to the outer periphery of the stator core. There is a fear that the movement of the crochet needle may be hampered by the projection of the crimped portion in the end surface of the stator core as compared to other portions in the end surface of the stator core where no projection of the crimped portion may be present. Therefore, the crimped portion may be disposed so as not to hamper the movement of the lacing crochet needle and located at a position adjacent to the outer periphery of the slot. However, the provision of the crimped portion at a position adjacent to the outer periphery of the slot may pose a problem in that the flow of magnetic flux in the stator core is impeded. Furthermore, when the electric compressor is small-sized or when the number of poles of the motor is increased, the teeth space and the width of the yoke that is adjacent to the bottom of the slot become smaller, which makes it difficult for the lacing crochet needle to be free from interference with the projection of the crimped portion.
The present invention, which has been made in light of the above problems, is directed to providing an electric compressor in which the coil end can be laced securely by a string and the interference between the crochet needle and the crimped portion is prevented successfully.